I would strongly suggest OP try and get a valid state-issued ID if at all possible. While technically not required, you are really playing agent roulette here (both DL and TSA). Why not get one, and alleviate the stress? If the passport wasn’t being renewed that would be the obvious solution. And also, I wouldn’t want my child traveling alone without proper ID in case things really went sideways. To be denied entry on the outbound is one thing, but imagine if it were to happen on the return in a strange city.